Copy the web socket stuff from http_parser.

lib/src/copy/bytes_builder.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This is a copy of "dart:io"'s BytesBuilder implementation, from
+// sdk/lib/io/bytes_builder.dart. It's copied here to make it available to
+// non-"dart:io" applications (issue 18348).
+//
+// Because it's copied directly, there are no modifications from the original.
+//
+// This is up-to-date as of sdk revision
+// 86227840d75d974feb238f8b3c59c038b99c05cf.
+import 'dart:math';
+import 'dart:typed_data';
+
+/**
+ * Builds a list of bytes, allowing bytes and lists of bytes to be added at the
+ * end.
+ *
+ * Used to efficiently collect bytes and lists of bytes.
+ */
+abstract class BytesBuilder {
+  /**
+   * Construct a new empty [BytesBuilder].
+   *
+   * If [copy] is true, the data is always copied when added to the list. If
+   * it [copy] is false, the data is only copied if needed. That means that if
+   * the lists are changed after added to the [BytesBuilder], it may effect the
+   * output. Default is `true`.
+   */
+  factory BytesBuilder({bool copy: true}) {
+    if (copy) {
+      return new _CopyingBytesBuilder();
+    } else {
+      return new _BytesBuilder();
+    }
+  }
+
+  /**
+   * Appends [bytes] to the current contents of the builder.
+   *
+   * Each value of [bytes] will be bit-representation truncated to the range
+   * 0 .. 255.
+   */
+  void add(List<int> bytes);
+
+  /**
+   * Append [byte] to the current contents of the builder.
+   *
+   * The [byte] will be bit-representation truncated to the range 0 .. 255.
+   */
+  void addByte(int byte);
+
+  /**
+   * Returns the contents of `this` and clears `this`.
+   *
+   * The list returned is a view of the the internal buffer, limited to the
+   * [length].
+   */
+  List<int> takeBytes();
+
+  /**
+   * Returns a copy of the current contents of the builder.
+   *
+   * Leaves the contents of the builder intact.
+   */
+  List<int> toBytes();
+
+  /**
+   * The number of bytes in the builder.
+   */
+  int get length;
+
+  /**
+   * Returns `true` if the buffer is empty.
+   */
+  bool get isEmpty;
+
+  /**
+   * Returns `true` if the buffer is not empty.
+   */
+  bool get isNotEmpty;
+
+  /**
+   * Clear the contents of the builder.
+   */
+  void clear();
+}
+
+
+class _CopyingBytesBuilder implements BytesBuilder {
+  // Start with 1024 bytes.
+  static const int _INIT_SIZE = 1024;
+
+  int _length = 0;
+  Uint8List _buffer;
+
+  void add(List<int> bytes) {
+    int bytesLength = bytes.length;
+    if (bytesLength == 0) return;
+    int required = _length + bytesLength;
+    if (_buffer == null) {
+      int size = _pow2roundup(required);
+      size = max(size, _INIT_SIZE);
+      _buffer = new Uint8List(size);
+    } else if (_buffer.length < required) {
+      // We will create a list in the range of 2-4 times larger than
+      // required.
+      int size = _pow2roundup(required) * 2;
+      var newBuffer = new Uint8List(size);
+      newBuffer.setRange(0, _buffer.length, _buffer);
+      _buffer = newBuffer;
+    }
+    assert(_buffer.length >= required);
+    if (bytes is Uint8List) {
+      _buffer.setRange(_length, required, bytes);
+    } else {
+      for (int i = 0; i < bytesLength; i++) {
+        _buffer[_length + i] = bytes[i];
+      }
+    }
+    _length = required;
+  }
+
+  void addByte(int byte) => add([byte]);
+
+  List<int> takeBytes() {
+    if (_buffer == null) return new Uint8List(0);
+    var buffer = new Uint8List.view(_buffer.buffer, 0, _length);
+    clear();
+    return buffer;
+  }
+
+  List<int> toBytes() {
+    if (_buffer == null) return new Uint8List(0);
+    return new Uint8List.fromList(
+        new Uint8List.view(_buffer.buffer, 0, _length));
+  }
+
+  int get length => _length;
+
+  bool get isEmpty => _length == 0;
+
+  bool get isNotEmpty => _length != 0;
+
+  void clear() {
+    _length = 0;
+    _buffer = null;
+  }
+
+  int _pow2roundup(int x) {
+    --x;
+    x |= x >> 1;
+    x |= x >> 2;
+    x |= x >> 4;
+    x |= x >> 8;
+    x |= x >> 16;
+    return x + 1;
+  }
+}
+
+
+class _BytesBuilder implements BytesBuilder {
+  int _length = 0;
+  final List _chunks = [];
+
+  void add(List<int> bytes) {
+    if (bytes is! Uint8List) {
+      bytes = new Uint8List.fromList(bytes);
+    }
+    _chunks.add(bytes);
+    _length += bytes.length;
+  }
+
+  void addByte(int byte) => add([byte]);
+
+  List<int> takeBytes() {
+    if (_chunks.length == 0) return new Uint8List(0);
+    if (_chunks.length == 1) {
+      var buffer = _chunks.single;
+      clear();
+      return buffer;
+    }
+    var buffer = new Uint8List(_length);
+    int offset = 0;
+    for (var chunk in _chunks) {
+      buffer.setRange(offset, offset + chunk.length, chunk);
+      offset += chunk.length;
+    }
+    clear();
+    return buffer;
+  }
+
+  List<int> toBytes() {
+    if (_chunks.length == 0) return new Uint8List(0);
+    var buffer = new Uint8List(_length);
+    int offset = 0;
+    for (var chunk in _chunks) {
+      buffer.setRange(offset, offset + chunk.length, chunk);
+      offset += chunk.length;
+    }
+    return buffer;
+  }
+
+  int get length => _length;
+
+  bool get isEmpty => _length == 0;
+
+  bool get isNotEmpty => _length != 0;
+
+  void clear() {
+    _length = 0;
+    _chunks.clear();
+  }
+}